CN104152718B - A method for synchronously separating tin and iron from tin-containing iron tailings - Google Patents

Abstract

The invention discloses a method for synchronously separating tin and iron from tin-containing iron tailings. The method comprises mixing the raw materials of tin-containing iron tailings and a compound additive composed of sodium sulfate, borax and sodium fulvic acid in a certain proportion. , agglomerated, dried, followed by oxidation roasting, reduction roasting and magnetic separation to obtain iron concentrates with less than 0.08% tin residue and tin-rich tailings with a grade greater than 1%, and the recovery rate of iron reaches more than 80%. , realized the high-efficiency separation of iron and tin in tin-iron tailings; this method has little pollution, low cost, and realizes the deep comprehensive utilization of tin-containing iron tailings resources, and is especially suitable for processing tin-iron symbiosis close relationship, using existing beneficiation The method is difficult to separate and recover tin-containing iron tailings resources.

Description

A method for synchronously separating tin and iron from tin-containing iron tailings

technical field

The invention relates to a method for comprehensive utilization of tin-containing iron tailings, in particular to a method for separating tin and iron from tin-containing iron beneficiation tailings by using a combined roasting method of oxidation roasting and then magnetization roasting, which belongs to mineral processing and nonferrous metals metallurgical field.

Background technique

The typical characteristics of my country's tin ore resources are: most of them are skarn-type vein tin deposits with deep burial and overlapping distribution. And the difficulty and high cost of smelting. At present, the domestic tin ore reserves are about 3 million tons, while the recoverable reserves are only about 1.5 million tons. Due to the long-term mining and the weakening of geological work in recent years, coupled with the disorderly mining of small-scale enterprises in the past few years, the level of beneficiation technology adopted is generally not high, resulting in the lack of reserve resources in most tin mines, which has caused serious damage to the dominant position of tin resources in my country. The potential threat has seriously affected the healthy and sustainable development of the domestic tin industry. Judging from the current utilization degree, output and consumption of tin resources in my country, the guarantee period for tin resources is less than 20 years.

With the depletion of tin ore resources and the rising price of metal tin, the minable grade of tin ore is decreasing year by year. At present, the mining grade of placer tin ore is reduced to 0.009%-0.03%, and the lowest is only 0.005%. It is about 0.5%.

After years of beneficiation process, the total amount of tin-containing tailings accumulated by major domestic beneficiation plants has reached more than 500 million tons, and is still increasing at a rate of more than 10 million tons per year. The average grade of tin in tin-containing tailings is 0.1% to 0.2%, and the total amount of metal tin after conversion reaches more than 700,000 tons. According to reports, the tin-containing tailings of Yunnan Yunxi Company alone reached 240 million tons, with a tin grade of about 0.18% and an average iron grade of more than 30%.

At present, the recycling methods of cassiterite minerals at home and abroad mainly include gravity separation, flotation and fuming volatilization (including sulfide volatilization, chlorination volatilization and reduction volatilization).

Gravity separation is mainly to use the characteristic that the density of cassiterite is higher than that of paragenetic gangue minerals. Its production cost is low and the environmental pollution is small. It is one of the main methods of producing cassiterite concentrate at home and abroad. At present, more than 85% of the world's tin production comes from gravity Mineral dressing. However, since placer tin ore contains a large amount of fine-grained slime, classification and desliming is a necessary preparatory operation in the process of cassiterite gravity separation. This operation needs to strictly control the selected particle size and eliminate the interference of the slime as much as possible. However, the separation of tin ore generally adopts the process of combining multi-stage grinding and separation. Due to the high brittleness of cassiterite, cassiterite is easy to be crushed during the grinding process, so that the fine particles are discarded with the tailings, resulting in a huge waste of resources. waste.

Flotation is aimed at fine-grained and complex ores accompanied by various valuable elements. After the ore is ground to the dissociation of monomers, fine-grained cassiterite can be effectively recovered. However, with the depletion of high-grade tin ore resources, the ore that needs to be processed by the flotation process is becoming more and more poor, fine, and impurity, and the difficulty of flotation is becoming more and more difficult. In addition, the flotation of cassiterite often needs to consider the associated recovery. Therefore, the flotation process faces practical problems such as high content of fine particles, pulp pH, and chemical system, which increases the difficulty of flotation and reduces the product recovery rate, resulting in the comprehensive recovery rate of tin being below 30%. Even lower, the flotation cassiterite beneficiation tailings still contain 0.1% to 0.2% tin which has not been effectively recovered. Therefore, a single flotation method can no longer meet the needs of low-grade tin ore recovery.

Vulcanization and chlorination fuming volatilization are currently more effective methods for treating low _- grade tin-containing iron resources, which can achieve better separation of tin and iron. The material is evenly mixed with reducing agent, vulcanizing agent or chlorinating agent and then roasted at high temperature. During the roasting process, tin enters the gas phase in the form of stannous compound, is cooled in the tail gas and recovered in the smoke. The tin recovery rate of fuming volatilization method is high, but there are high roasting temperature and long roasting time, and toxic and harmful gases such as SO ₂ and Cl ₂ are formed during the roasting process, which not only pollutes the environment, but also corrodes the equipment. The above defects have seriously limited the industrial application of the fuming volatilization process. The patent "A method for separating and recovering tin from tin-containing tailings in mineral processing (Patent No.: 201210453731.2)" uses weak reduction roasting method to treat tin-containing mineral processing tailings that are difficult to handle by traditional mineral processing technology, so that the tin The volatilization rate is over 70%. The technical principle is: under high temperature conditions, the use of SnO ₂ is easier to reduce to SnO, and the vapor pressure of SnO is large, so as to realize the volatilization and recovery of SnO. However, this method does not involve the recovery of iron in tailings, and the recovery rate of tin is still not high. According to thermodynamic analysis, the volume concentration [CO/(CO+CO ₂ )] of CO in the roasting atmosphere of this method is 20% to 50%. Follow-up iron recovery and utilization.

In summary, it is difficult to achieve efficient separation and recovery of tin-iron resources with complex symbiotic relationships by using the existing beneficiation technology, the resulting tin recovery rate is low, and the tin content in iron concentrate exceeds the requirements for raw materials for blast furnace smelting (requires Sn content below 0.08%), while the fuming volatilization process has the disadvantages of high energy consumption, high cost, and large pollution. Therefore, the development of economical and efficient utilization of tin-bearing iron ore resources, especially the rich reserves of refractory tin-bearing iron tailings resources, can effectively alleviate the tight supply of tin resources and iron ore resources in my country.

Contents of the invention

Aiming at a series of defects such as low separation efficiency and high cost in the process of processing tin-iron tailings in the prior art, the purpose of the present invention is to provide a kind of tin-iron tailings as raw material, which can realize high efficiency of iron and tin in tin-iron tailings. Separation, little pollution, and low cost, the method realizes the deep comprehensive utilization of resources and meets the requirements of industrial production.

The invention provides a method for synchronously separating tin and iron from tin-containing iron tailings, the method comprising the following steps:

Step (1): Blocking of raw materials

After mixing the tin-containing iron tailings and the composite additive at a mass ratio of 100:7-10, the mixed material is agglomerated; the composite additive is composed of the following components in mass percentage: 10%-20% of sodium sulfate, 50% of borax ～70%, sodium fulvic acid 20%～30%;

Step (2): Oxidation Roasting

The agglomerate obtained in step (1) is pre-dried, placed in an oxidizing atmosphere, and oxidized and roasted at a temperature of 800°C to 900°C to obtain an oxidized roasted agglomerate; the oxidizing atmosphere is composed of a mixture of _O2 and _N2 , The volume percentage of O ₂ in the oxidizing atmosphere [O ₂ /(O ₂ +N ₂ )]×100%≥10%;

Step (3): Magnetization roasting

Place the oxidized and roasted agglomerate obtained in step (2) in a reducing atmosphere, and perform reduction and roasting at a temperature of 550° C. to 750° C. After the reduction and roasting is completed, cool in an inert atmosphere to obtain a reduction and roasting product; the reducing atmosphere Composed of a mixture of CO and CO ₂ , the volume percentage of CO in the reducing atmosphere is maintained at 5%≤[CO/(CO+CO ₂ )]×100%≤25%;

Step (4): Grinding and Magnetic Separation

After grinding the reduced roasted product obtained in step (3), magnetic separation is used to obtain magnetite concentrate and tin-rich tailings.

The method for synchronously separating tin and iron from tin-containing iron tailings of the present invention also includes the following preferred schemes:

In a preferred solution, the oxidation roasting time is 35 minutes to 65 minutes.

In a preferred scheme, the reduction roasting time is 25 minutes to 65 minutes.

In a preferred solution, the reduced roasted product in step (4) is ground until the particle size is -0.074 mm, and the mass percentage content is ≥ 80%.

In the preferred solution, the magnetic separation in step (4) is realized in a magnetic field with a magnetic field strength of 800Gs-1500Gs.

In the preferred scheme, the iron grade of the magnetite concentrate obtained in step (4) is ≥60%, and the tin content is <0.08%; the tin grade of the obtained tin-rich tailings is>1%.

The agglomeration method includes pelletizing or briquetting.

The innovation of the present invention lies in: firstly, the present invention has carried out a large number of researches on the phase of tin in tin-containing iron tailings, and found that the existence of non-cassiterite state tin is the recovery of tin in the process of separation and recovery of tin-containing ore by mineral processing. important reason for the low rate. The existing beneficiation processes are generally aimed at cassiterite (SnO ₂ ) minerals, and the recovery of non-cassiterite tin phases is hardly considered, so such tin minerals are enriched in tailings. In some tin-bearing iron tailings, the mass percentage of non-cassiterite tin in the total tin is even higher than 50%. The inventors conducted a large number of further experimental studies and found that non-cassiterite tin minerals are mainly cassiterite and tin sulfide phases, which can undergo decomposition or oxidation reactions under oxidative roasting conditions, and finally form tin dioxide. At the same time, the inventor has done a lot of experimental research on the roasting process of tin-containing iron tailings, and found that the composite additive composed of borax, sodium sulfate and sodium fulvic acid in a certain proportion helps to strengthen the iron tailings under the conditions of oxidation roasting and magnetization roasting. The separation of tin and iron, and the agglomerates can ensure a better shape during drying and roasting, and basically no powder is produced. Therefore, the present invention finally determines the combination of oxidation roasting, magnetization roasting and magnetic separation separation, which can realize the phase conversion of non-cassiterite tin in the tailings into tin dioxide and enrich it in the magnetic separation tailings. And reduce the high-valent iron oxides in the original tailings to magnetite, and then obtain the magnetite concentrate through grinding and magnetic separation.

Compared with the prior art, the beneficial effect of the present invention is: the iron recovery rate of the magnetically separated iron concentrate can reach more than 80%, wherein the tin residue is less than 0.08%, which meets the requirements of raw materials for blast furnace ironmaking; tin mainly It is enriched in the tailings in the form of tin dioxide, which can be separated and recovered by the existing beneficiation methods for cassiterite minerals. Compared with the existing methods, the present invention also has the advantages of low roasting temperature, short time, and remarkable tin-iron separation effect, etc., and is especially suitable for treating tin-iron-containing iron that has a close symbiotic relationship and is difficult to separate and recover by existing beneficiation methods tailings. By adopting the technology provided by the invention, the iron and tin in the tin-iron tailings can be efficiently separated, thereby realizing the comprehensive recycling and value-added processing of the refractory tin-containing iron tailings.

Description of drawings

[Fig. 1] is a process flow diagram of the present invention.

Detailed ways

The following examples are intended to further illustrate the content of the present invention, rather than limit the protection scope of the present invention.

Comparative Example 1

Do not add composite additive of the present invention in this comparative example, also do not carry out oxidative roasting:

First, dehydrate and dry the tin-containing iron tailings (0.45% tin grade, 40.21% iron grade) to a certain amount of water, then make agglomerates and dry them; put the dried agglomerates into a roasting furnace, and roast them at a roasting temperature of 600°C , the volume concentration [CO/(CO+CO ₂ )]×100% of CO in the reducing gas is 15%, and the roasting time is _65min . To 80% less than 0.074mm, magnetic separation under the condition of magnetic field intensity of 1000Gs, to obtain iron concentrate with an iron grade of 61.12% (the grade of tin is 0.32%), the iron recovery rate is 80.21%, and the grade of tin in the tin-rich tailings is obtained 0.55% (66.3% of tin exists as tin dioxide). The separation effect of tin and iron is poor, and the tin grade of iron concentrate obtained by magnetic separation is much higher than 0.08%, so it cannot be directly used as a blast furnace charge.

Comparative Example 2

Added composite additive of the present invention in this comparative example, but did not carry out oxidative roasting:

First, the tin-containing iron tailings (tin grade 0.83%, iron grade 34.21%) are dehydrated and dried to a certain amount of water, and then compound additives that account for 7% of the tailings (dry basis) by mass (the mass ratio of different components is sulfuric acid Sodium: borax: sodium fulvic acid = 10%: 70%: 20%), after mixing the materials evenly, agglomerate and dry; the dried agglomerate is put into a roasting furnace and roasted at a roasting temperature of 550°C , the volume concentration [CO/(CO+CO ₂ )]×100% of CO in the reducing gas is 25%, and the calcination time is _65min . To 80% less than 0.074mm, magnetic separation under the condition of magnetic field strength of 800Gs, to obtain iron concentrate with an iron grade of 60.23% (the grade of tin is 0.33%), the iron recovery rate is 81.14%, and the grade of tin in the tin-rich tailings is obtained 1.02% (79.9% of tin exists as tin dioxide). The separation effect of tin and iron is poor, and the tin grade of iron concentrate obtained by magnetic separation is much higher than 0.08%, so it cannot be directly used as a blast furnace charge.

Example 1

First, the tin-containing iron tailings (0.55% tin grade, 40.21% iron grade) are dehydrated and dried to a certain amount of moisture, and then compound additives that account for 10% of the mass percent of the tailings (dry basis) are added (the mass ratio of different components is sulfuric acid Sodium: borax: sodium fulvic acid = 10%: 70%: 20%), after the materials are mixed evenly, agglomerate, dry; the agglomerate after drying is put into roasting furnace, feed into nitrogen protection, be warming up to 900 ℃, after the temperature is stabilized, the volume concentration of O ₂ [O ₂ /(O ₂ +N ₂ )]×100% is 10% mixed gas for roasting for 35 minutes, and then the temperature is lowered to 750 ℃, and the CO in the reducing gas The volume concentration [CO/(CO+CO ₂ )]×100% is 5%, and the calcination time is 25min. After the calcination is completed, the calcination agglomerate is cooled under N ₂ atmosphere, and ground to 80% less than 0.074mm. Magnetic separation under the condition of intensity of 1000Gs. A magnetite concentrate with an iron grade of 64.31% (with a tin grade of 0.05%) was obtained, with an iron recovery rate of 83.11%, and a tin grade of 1.12% in tin-rich tailings (94.1% of which was present as tin dioxide).

Example 2

First, the tin-containing iron tailings (tin grade 0.83%, iron grade 34.21%) are dehydrated and dried to a certain amount of water, and then compound additives that account for 7% of the tailings (dry basis) by mass (the mass ratio of different components is sulfuric acid Sodium: borax: sodium fulvic acid = 20%: 50%: 30%), after the materials are evenly mixed, agglomerate, dry; the agglomerate after drying is put into the roasting furnace, pass into nitrogen protection, be warming up to 850 ℃, after the temperature is stabilized, pass in a mixed gas with O ₂ volume concentration [O ₂ /(O ₂ +N ₂ )]×100% of 21% to roast for 40 minutes, then lower the temperature to 550 ℃, and pass in CO in reducing gas The volume concentration of [CO/(CO+CO ₂ )]×100% is 25%, and the roasting time is _65min . Magnetic separation under the condition of a magnetic field strength of 800Gs, the iron concentrate with an iron grade of 62.34% (wherein the grade of tin is 0.07%), the iron recovery rate is 84.22%, and the grade of tin in the rich tin tailings is 1.66% (wherein 94.3% of tin present as tin dioxide).

Example 3

First, the tin-containing iron tailings (1.13% tin grade, 42.24% iron grade) are dehydrated and dried to a certain amount of water, and then compounded with 8% of the tailings (dry basis) mass percentage (the mass ratio of different components is sulfuric acid Sodium: borax: sodium fulvic acid = 15%: 63%: 22%), after the materials are mixed evenly, agglomerate, dry; The agglomerate after drying is put into roasting furnace, feeds nitrogen protection, is heated up to 800 ℃, after the temperature is stabilized, the volume concentration of O ₂ [O ₂ /(O ₂ +N ₂ )]×100% is 40% mixed gas for roasting for 65 minutes, and then the temperature is lowered to 700 ℃, and the CO in the reducing gas The volume concentration [CO/(CO+CO ₂ )]×100% is 10%, and the calcination time is 55min. After the calcination, the calcination agglomerate is cooled under the N ₂ atmosphere, and ground to 80% less than 0.074mm. Magnetic separation under the condition of intensity of 1500Gs. An iron concentrate with an iron grade of 60.34% (with a tin grade of 0.05%) was obtained, with an iron recovery rate of 85.34%, and a tin grade of 2.01% in the tin-rich tailings (wherein 96.5% of the tin exists as tin dioxide).

Example 4

First, the tin-containing iron tailings (1.02% tin grade, 26.43% iron grade) are dehydrated and dried to a certain amount of water, and then compound additives (the mass ratio of different components is sulfuric acid) that account for 9% of the tailings (dry basis) mass percentage are added. Sodium: borax: sodium fulvic acid = 17%: 60%: 23%), after the materials are mixed evenly, agglomerate, dry; The agglomerate after drying is put into roasting furnace, feeds nitrogen protection, is warming up to 830 ℃, after the temperature is stabilized, pass in a mixed gas with a volume concentration of O ₂ [O ₂ /(O ₂ +N ₂ )]×100% of 55% and roast for 50 minutes, then lower the temperature to 650 ℃, and pass in CO in reducing gas The volume concentration [CO/(CO+CO ₂ )]×100% is 20%, and the roasting time is 40min. After the roasting is completed, the roasted agglomerate is cooled under N ₂ atmosphere, and ground to 80% less than 0.074mm. Magnetic separation under the condition of a magnetic field strength of 1100Gs. An iron concentrate with an iron grade of 60.34% (tin grade 0.07%) was obtained, with an iron recovery rate of 84.34%, and a tin grade of 1.66% in the tin-rich tailings (wherein 95.8% of the tin exists as tin dioxide).

Claims (6)

1. a method for stanniferous iron tailings separated in synchronization tin and iron, is characterized in that, comprise the following steps:

Step (1): raw material agglomeration

After by stanniferous iron tailings, 100:7 ~ 10 mix in mass ratio with composite additive, by mixture agglomeration; Described composite additive is made up of following mass percent component: sodium sulfate 10% ~ 20%, borax 50% ~ 70%, SODLUM FULVATE 20% ~ 30%;

Step (2): oxidizing roasting

Step (1) gained agglomerate, after predrying, is placed in oxidizing atmosphere, carries out oxidizing roasting, obtain oxidizing roasting agglomerate at 800 DEG C ~ 900 DEG C temperature; Described oxidizing atmosphere is by O ₂and N ₂mixing composition, O in oxidizing atmosphere ₂volume percent mark [O ₂/ (O ₂+ N ₂)] × 100%>=10%;

Step (3): magnetizing roasting

Step (2) gained oxidizing roasting agglomerate is placed in reducing atmosphere, at 550 DEG C ~ 750 DEG C temperature, carries out reducing roasting, after reducing roasting completes, cool in an inert atmosphere, obtain reducing roasting product; Described reducing atmosphere is by CO and CO ₂mixing composition, in reducing atmosphere, the volume percent fractal dimension of CO is held in 5%≤[CO/ (CO+CO ₂)] × 100%≤25%;

Step (4): mill ore magnetic selection

After the reducing roasting product that step (3) obtains is milled, be separated by magnetic separation and obtain magnetite concentrate and rich tailing.

2. method according to claim 1, is characterized in that, the oxidizing roasting time is 35min ~ 65min.

3. method according to claim 1, is characterized in that, the reducing roasting time is 25min ~ 65min.

4. method according to claim 1, is characterized in that, described reducing roasting product is milled until granularity mass percentage content >=80% shared by-0.074mm.

5. method according to claim 1, is characterized in that, it is be realize in the magnetic field of 800Gs ~ 1500Gs in magneticstrength that described magnetic separation is separated.

6. the method according to any one of Claims 1 to 5, is characterized in that, magnetite concentrate Iron grade >=60% of gained in step (4), the mass content < 0.08% of tin; Tin grade > 1% in the rich tailing of gained.